A Journey to the Earth's Interior

THE MAN whose acquaintance with cosmogony and physiography is confined to what he learned in school, and, perhaps, afterward read in popular publications, has certain very definite notions about the shape of the earth and the construction of its interior. These notions, he thinks, are based upon the proven discoveries, or the impregnable theories of the scientists, and so he accepts them in blind faith. But the scientists themselves do not rest under the impression that they have solved every mystery that is buried in the bowels of the earth. While they hold to a general theory about the shape and constitution of the earth, that it is a rigid solid--a theory which is now beginning to supersede the older theory that it was a shell with a liquid interior--they admit that there are many questions raised by recent observations of facts that cannot be explained by their present theory.